Local iterated function system (LIFS) image coding is currently a main topic of fractal image coding and is being studied from various points of view. However, its performance is still inferior to conventional schemes such as JPEG.

This paper proposes a novel local transformation called extended condensation and reports that the LIFS coding scheme is significantly improved by combining the technique with Ida's average separation scheme. When the compression ratio is high, a better decoded image is acquired by the proposed scheme than by JPEG.